Durability questions...

I'm considering building a cob house with as little outside bought material as possible. Both for financial reasons, and I really like the idea of creating a home from materials that come from my own land. My husband, however, isn't convinced. He's worried about how tough and waterproof it will be.
Can you water-mop an earthen floor? If something really greasy and nasty ends up on the floor, could I use a scrub brush or would that dig into the floor? What sort of soap would you use? I currently use Murphy's oil soap on my antique wood floors, would that work?
If the floor is properly tamped down, will dog nails scratch the floor? What about doggie 'accidents'? Or if someone drags their feet or wears spike heels? I understand it is easy to repair yourself, but I don't want that to be a new daily job...

Like many things, it depends.  The good news is earthen floors can be quite durable.  However, it depends on the mix of floor material and how you seal/finish it.  Easily damaged earthen floors usually have too little sand (too much clay) or weren't sealed and finished enough.

We have earthen floors with radiant heat in our house in all rooms except the bathroom and foyer.  The floor was sealed with linseed oil (with citrus thinner) and then two coats of a hardwood floor finish.

We wet mop the floor frequently (it does not absorb any water).  Greasy spills are no problem, though you don't want to leave a serious degreaser on the floor for too long since it will damage the hardwood finish.  A scrub brush would be o.k. as long as it has plastic or natural fiber bristles.  A metal wire brush would damage it.  Dog nails or normal shoes don't scratch.  Though boots with sand/gravel stuck in the treads will scratch.  Furniture with small, hard feet may make small dents.  Also, I dropped a dutch oven that made a small dent.  We have rugs under the rolling office chair and living room furniture to prevent wear.

My husband and I have lived on our earthen floor for a few years now, and have had almost the same experience as Ardilla.
The oil finishing process is so key.  Straight linseed oil on the first coat, and slowly more and more orange oil solvent added with additional layers.  Hardwood floor finish is an interesting idea.  I know many folks choose to wax also.
With adequate oil, though, the floor will actually NOT get scratched even with a wire brush.  I've tried.  The reason I tried is because I have had to patch the floor in a couple areas.
During periods of high humidity and hot weather (I'm in Arkansas) the floor will soften to the point that if a person sits in a chair with pointy legs for too long, the floor will dent.  When I tried to dig out the dent and abrade the adjacent floor, I found I could chisel through the oil layer, but nothing but nothing would abrade it.  It took the sand right off of sandpaper.  Quite impressive really.
I had thought if I could abrade the oil layer off of the area surrounding the patch, I'd be able to blend the new patch in better.  But instead, I settled for washing any cob smears off of the adjacent oiled floor and oiling the patch to match.  As long as I burnished a few times during the drying process, I was able to prevent any cracking between old and new and the result looks good to me.

I concur, properly mixed installed adobe earth cob floors are incredibly durable, washable and patchable!

Hello,
I'm not sure if this is okay to ask here, but it goes along with durability issues of earthen floors. We made a rocket mass heater next to our bathroom, which we will use start using as a hot water heater next winter. I would like to put an earthen floor alongside it, as a buffer before the heater and a wood floor. But I worry about the fact that it would be applied on top of a very rough concrete. Does anyone know if the concrete would cause durability issues?
Good day to all of you.
Tiffany in Brittany

Tiffaney Dex wrote:Hello,
I'm not sure if this is okay to ask here, but it goes along with durability issues of earthen floors. We made a rocket mass heater next to our bathroom, which we will use start using as a hot water heater next winter. I would like to put an earthen floor alongside it, as a buffer before the heater and a wood floor. But I worry about the fact that it would be applied on top of a very rough concrete. Does anyone know if the concrete would cause durability issues?
Good day to all of you.
Tiffany in Brittany

Tiffany, there are additional variables.  How thick is the cob layer, is there straw or another reinforcing and binding material added to the floor mix.  And considering the rough concrete, how rough?

I’m imagining very rough, with sharp peaks.  Where the cob material passes over the sharp concrete peak, the floor material will be the thinnest.  I’m not an engineer, nor a professional, nor have I ever done this.  It’s just my thought experiment.  I think where the floor is the thinnest, it would likely be the least durable.  If an extreme point load were to press down on the point above the concrete point, the floor material might fail, it could be crushed.

Lotta points in that sentence!

Anyway if you minimize the pointyness of the concrete below, or have room for a thick enough layer of floor material that the load is dispersed as it travels through the floor, seems like you would minimize the chances of floor failure.

An engineer, or a person with experience with this may come along and post a different answer.  I would take their recommendations over mine thought experiment.

Good luck

Thank you, Thekla, for sharing your thoughts on it with me. The thickest part of the earthen floor would be 9 centimetres thick. The rough concrete isn't as rough as you imagined. A previous owner layed it with the idea that something else would be put on top of it, so the surface was not made as a smooth slab, but has lots of smooth round pebbles all over.

But part of it that I wasn't asking about earlier would only be two centimeters thick. That floor was actually completed and tiles were laid by a different previous owner. So that part is smooth. We had planned to put a thin wood floor over the tiles, but we figured out during the winter that we have to get rid of all of the wood that comes in contact with the mass rocket heater before next winter. I really dislike tile floors but my husband is worried about an earthen floor not holding up.

In my experience, a 2 cm earth floor over tiles will crack up.
Its just not thick enough to have inherent strength.

A 2 cm floor might be at the boundary between it’ll work and it won’t.

How hard would it be to get the tile and mortar up?  What do your sources say about how thick to make an earthen floor?  I just did a quick search, recommended thickness 3/4 inch to 2 inches.

Hard use needs a thicker floor.

Keep us posted on your progress!

An expert may be along soon🤣

Or check if there’s a thread on earthen floors here on permies, that might be where the experts are.